The snapshot below is a of a rig running 7 RX 570s, all with stock bios, and no OC settings applied (ever) via the Dashboard.
As you can see, two of them have switched from the default 1128 to 1191.
This seemingly happens at random to different GPUs across all of my rigs.
The change to 1191 is not random, however. A couple of my rigs currently have some GPUs with a custom bios which has a default core clock of 1191. The rig in the photo has not ever had anything but cards with the stock bios connected. I have also manually input 1191 as the core clock on other rigs of mine, but I have never applied an OC to the rig in the picture.
Changing the core clock settings in smOS does not seem to have any effect. It will change the clock upon startup, but it may change again before mining even starts, without any notice in the terminal.
edit: 1128 is not even the stock clock according to MSI spec sheet, it is actually 1268. So why is smOS automatically downclocking my cards???
it is using linux drivers not windows which may vary a bit